Workers are aware that new and innovative high speed document transport systems are desirable. Workers are active in this field. Examples are described in U.S. Pat. Nos.: 5,029,845, 4,974,680, 5,098,082, 5,172,900, 4,903,954, 4,346,883, 4,425,694. Many such systems have typically employed opposed pinch-rolls and to accommodate variance in document thickness etc., have used resilient means therewith.
Previous resilient elements, such as air dashpots, bushings, sliding contact devices, and magnetic devices, require small gaps between components. These gaps collect paper dust which can interfere with normal functioning of the (movable) pinch roller. Other devices employ flexible damping material in the pinch roll (roller) itself. But this can cause overheating in the roller due to its constant rotation with a pinch load.
My invention avoids the foregoing problems, and involves means for damping a movable document transport pinch roller where the document transport must allow for gaps between documents, for documents of irregular thicknesses, and/or for unusual protrusions on the document such as staples and folds.
A salient object is to minimize transient motions of the movable pinch roll perpendicular to the document transport direction, so that the pinch rolls remain in intimate contact with the document at all times. Such transient motions occur where there are gaps between documents, irregular thicknesses, and/or protrusions such as staples or folds.
As a feature hereof, damping is provided through the use of a flexible damping material, such as poly-urethane, that also serves as a pivot bearing. A means of assembly prevents the damping material from experiencing a "static pro-load", and avoids related creep problems in the flexible damping material.
It is of particular interest to mount a movable pinch-roll or the like on an arm cantilevered-out from a pivot point defined by a fixed shaft, with this shaft surrounded by two concentric follow cylinders plus intermediate high-damping elastomeric material, as in FIG. 1.
Additionally, a resilient pre-load is preferably applied as in FIG. 1A (e.g. via a flexure).
Thus, it is an object hereof to address (at least some of) the aforementioned problems, and to provide the herein-cited advantages and functions. A related object is to provide a moving pinch-roll mounted on a pivot arm, whose pivoting is resiliently resisted by flexible damping material.
The methods and means discussed herein, will generally be understood as constructed and operating as presently known in the art, except where otherwise specified; and with all materials, methods and devices and apparatus herein understood as implemented by known expedients according to present good practice.